S-91251A503 5/8"-18 x 3 1/4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 PSI ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the black-oxide finish extends service life in harsh industrial environments, minimizing maintenance needs.
• Precise Class 3A thread fit provides tighter tolerances for secure, vibration-resistant assemblies, enhancing joint integrity.
• Fine UNF threads offer improved load distribution and better adjustment control compared to coarse threads.
• High hardness (Rockwell C37) resists wear and deformation, ensuring long-term durability under repetitive loads.
• Partially threaded design allows for optimal clamping force on specific sections, preventing loosening in dynamic applications.
• Compliance with ASTM A574, RoHS 3, and REACH guarantees material quality and environmental safety for global industrial use.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical challenges in heavy-duty machinery, automotive, and aerospace sectors where vibration resistance and corrosion protection are paramount. The fine UNF threads and Class 3A fit ensure minimal backlash and secure fastening in high-precision assemblies, reducing downtime from loosening. Its high tensile strength and Rockwell C37 hardness make it ideal for applications subjected to dynamic loads and extreme conditions, providing reliable performance without compromising on environmental compliance. The 1/2" hex drive facilitates easy installation with standard tools, streamlining maintenance and assembly processes in industrial settings.

Specification Summary & Compliance

This socket head cap screw features a 5/8"-18 UNF fine thread with Class 3A thread fit for precision alignment and tight tolerances. It complies with ASTM A574 specifications for alloy steel socket head cap screws, ensuring consistent material and mechanical properties. The product is RoHS 3 (2015/863/EU) compliant and REACH (EC 1907/2006) compliant, meeting stringent environmental and safety standards for industrial use.